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* Urea Breath Test *

Helicobacter pylori (H. pylori) : is a spiral gram – negative bacterium, found deep in the mucous layer covering the lining of stomach but does not invade the gastric mucosa.
It plays a significant role in the pathogenesis of chronic gastritis, gastric, duodenal ulcers, and stomach cancer. Now H. pylori is classified as grade I carcinogen so patient with H. pylori have 3-6 times the normal stomach cancer risk.

H. pylori is a very special organism as it can survive and multiple in the acid environment of the stomach because it secretes enzymes called urease, converts urea into bicarbonate and ammonia which are strong bases, this creates acid neutralizing chemicals around the H. pylori, protecting it form acid in the stomach. Also it can protect itself against the immune system which send white cells and killer T cells but they can’t easily get through stomach lining in which H. pylori is present.

Mode of infection :

H. pylori can be transmitted orally by means of fecal matter through ingestion of waste food or water or exposure to vomit or saliva of infected person.

Symptoms of an ulcer :

• Abdominal discomfort is the most common symptom and its usually dull, comes and goes for several days occurs 2-3 hrs after meal, mainly in middle of night and relieved by eating.
• Other symptoms include : weight loss, poor appetite, nausea and vomiting

Diagnosis of H. pylori :

Direct detection by invasive techniques, which required endoscopy as :
1) Endoscopic gastric biopsy : must include superficial epithelium, fixed in 10%
buffered formalin and processed routinely. When H. pylori is present the
biopsy shows the histologic changes of chronic active gastritis.

2) Culture of gastric biopsy specimens : biopsy culture has the advantage to
isolate H. pylori for antibiotic susceptibility but this technique is not often
used as many factors may lead to unsuccessful growth including culturing part
of specimen containing no bacteria, contamination with other organisms or
recent use of antibiotics that can inhibit bacterial growth.




Non invasive diagnostic tests :

1) Urea breath test (UBT); A capsule of urea that has been labelled with a carbon
isotope C13 or C14 is taken orally with a glass of water (patient should be
fasting 4-6 hrs), 10 minutes after taking the capsule the patient start to expire
into urea breath card (plastic bag) which has the advantage of being light, easy
to use, to send and also valid for reading for long time.

- In infected patients, the urea is hydrolyzed by bacterial urease to ammonia
and labeled bicarbonate, which diffuse into blood and identified in the
expired breath as labeled C02.

- UBT has excellent sensitivity for initial diagnosis of active infection.

- UBT should be repeated after 4-6 weeks from completing the therapy.

2) Non invasive test based on the detection of H. pylori antigen in stool
specimens was introduced. HpSa has the advantage of being easy, rapid simple
non invasive test for detection of H. pylori infection. HpSA also has high
sensitivity and specificity limits and evaluating treatment efficacy in
symptomatic infected patient or confirmation of eradication 4 weeks after the
end of treatment.

3) The most common non invasive approach for the detection of H. pylori is the
serological identification of specific Antibodies in infected patient using
enzyme linked immunosorbent assay (ELISA), which is the preferred method
based on its sensitivity, speed, low cost and simplicity, but the main
disadvantage of this approach is that antibodies persist for long time after
successful eradication, giving false positive results.




UBT considered the test of choice it is available on daily basis.

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